ESR and magnetic studies of nickel ions doped P2O5–ZnO–Na2O glassy system

Abstract

We prepared 42P₂O₅–40ZnO–(18-x)Na₂O–(x)NiO glasses doped with xNiO where 1 ≤ x ≤ 6 mol.%. The optical absorption indicates that the nickel ions exist in both sites tetrahedral and octahedral as the concentration of NiO is increased. This investigation has provided the increasing degree of disorder in the glass network at higher concentrations of NiO. The magnetic characteristics investigated by two techniques electron spin resonance (ESR) spectra and magnetic properties using vibrating sample magnetometer (VSM) at room temperature. The ESR spectra exhibit resonance signal without hyperfine interaction of all the investigated glass samples. It is found that Ni²⁺ ions were in octahedral sites and it has ₃A^2g as ground state. The spin-Hamiltonian parameters are evaluated from the ESR spectra and we found a variation of   and   with different nickel concentration. Interesting results are found for the number of Ni²⁺ ions participating in resonance (N) and paramagnetic susceptibility (χ). The magnetic properties were performed at room temperature under an applied field of 20 kOe and the hysteresis loops of the powders were extracted for all the considered samples.